Hydraulic control system for elevators



July 26, 1960 A. W. PAULSON ETAL HYDRAULIC CONTROL SYSTEM FOR ELEVATORS 2 Sheets-Sheet 1 Filed Nov. 7, 1956 av ATTORNEY R m 3 3 S mm bk 3 &.

July 26, 1960 A. w. PAULSON ET AL 2,946,319

HYDRAULIC CONTROL SYSTEM FOR ELEVATORS Filed Nov. 7, 1956 2 Sheets-Sheet 2 BY fwd ATTORNEY United States HYDRAULIC CONTROL SYSTEM FOR ELEVATORS Arthur Willard Paulson, Old Greenwich, Conn., and

Andrew Fabula, Hohokus, NJ,, assignors to Otis Elevator Company, New York, N.Y., a corporation of New Jersey Filed Nov. 7, 1956, Ser. No. 620,881

7 Claims. (Cl. 121-41) This invention relates to an elevator control system and in particular to a hydraulic control system for a hydraulic machine.

It is customary to use hydraulic machines for raising and lowering elevators of unusually large size or for abnormally heavy loads. Such machines include valves to regulate the flow of motive fluid into and out of a cylinder causing movement of a plunger therein, and control means for automatic actuation of the valves.

One such hydraulic machine is illustrated in US. Patent No. 2,409,198 granted to J. Dunlop on October 15, 1946, wherein the valve ports are opened and closed by a reciprocating piston connected to a valve shaft whose longitudinal movement is controlled by a differential mechanism. The differential mechanism includes a restrained nut having external gear teeth meshing with a driving gear and internal threads meshing with a threaded portion on the valve shaft. The driving gear is connected to a follow-up mechanism movable in response to the plunger movement whereby rotary motion is imparted to the restrained nut. Rotary motion is transmitted to the valve shaft by reduction gearing which is driven by an electric motor. Different speeds of rotation between the restrained nut and the valve shaft cause the threaded portion of the valve shaft to move axially with the result that the attached piston changes its position relative to the valve ports.

Acceleration and decleration of the plunger is controlled by impairing the axial movement of the valve shaft. For this purpose the follow-up mechanism includes acceleration and deceleration cams which engage rollers mounted on a lever pivotally attached to the end of the valve shaft.

A disadvantage with the Dunlop arrangement arises in the event of failure of the electric power source, causing a shutdown of the elevator until the electric power is restored. Even though the hydraulic fluid is maintained at a pressure suflicient to raise and lower the elevator, there is no means, other than manual, to control the valve actuation because the power failure precludes the transmission of rotary motion to the valve shaft by the motor.

A further disadvantage with such arrangement resides in controlling the acceleration and deceleration of the elevator by impeding the axial movement of the valve shaft without any means to accelerate or decelerate the rotary motion of the valve shaft. The resulting disparity between the two speeds causes undue strain on the dif ferential mechanism as well as unstable movement of the elevator during its acceleration and deceleration stages.

It is therefore an object of this invention to overcome the above problems by utilizing a fluid motor to control a hydraulic machine and a hydraulic control system to control the fluid motor.

' Another object is to provide a hydraulic elevator machine with a fluid motor having a hydraulic control system which utilizes the same fluid source as the hy- 2,946,319 Patented July 26, 1960 ice draulic elevator machine. With such an arrangement as long as there is sufficient hydraulic pressure to raise or lower the elevator, there will be suflicient hydraulic pressure to control the operation of the elevator.

A further object is to provide a hydraulic elevator machine with an improved control system to control effectively the acceleration, constant speed and deceleration of the elevator.

It is a further object to provide a fluid control motor of a hydraulic machine with a hydraulic control system having directional valves to determine the direction of rotation of said motor and a servo-mechanism operable by said hydraulic machine to vary the speed of said motor by controlling the rate of actuation of said directional valves.

This invention has another object in that a hydraulic elevator machine is furnished with an improved quick closing valve operable by spring pressure through a rack and pinion to close partially the valve chamber of the machine whenever the fluid pressure drops below a predetermined value.

Additional features and advantages of the invention will be apparent from the following description of the drawings and appended claims.

In the drawings:

Figure 1 is a schematic representation in side elevation of an elevator mounted on the side of an aircraft carrier;

Figure 2 is a plan view showing the control mechanism of a hydraulic elevator machine, with portions broken away to illustrate certain details thereof;

. Figure 3 is a side view of Figure 2, with portions broken away to illustrate certain details thereof;

Figure 4 is a plan view showing the accelerating and decelerating cams for each directional valve;

Figure 5 is a schematic circuit diagram showing the main elements of the hydraulic control system;

Figure 6 is a view of the operating elements of the quick closing valve; and

Figure 7 is a sectional view taken on line 7--7 of.

Figure 6, with additional valve structure illustrated.

Referring first to Figure 1, there is shown the platform 10 of a deck-edge elevator operating between the flight deck 11 and the hangar deck 12 of an aircraft carrier.

Two sets of hoisting cables 13 and 14, illustrated as .single ropes, are secured to the elevator platform by cable hitches 15 and 16, respectively. Cables '13 pass over idlers 17 and 18, thence downwardly around idler 20 to the hoisting machine 21. Similarly, cables 14 pass over idlers 22, 23 and 24 to the hoisting machine 21.

The elevator platform is raised and lowered in response to the reciprocating motion of a plunger 25 in a cylinder 26. A plunger follower 28 is adjustably mounted on the exposed end of plunger 25 by any suitable means, such as a mounting bracket 27, so that the follower 28 will move simultaneously with the plunger 25 along suitable guides (not shown).

Movement of the plunger is effected by the flow of fluid into the cylinder for raising the elevator and out of the cylinder for lowering the elevator while such fluid flow is regulated by the main control valve 30 and the leveling valve 46. The main control valve 30 (Figure 3) comprises an intake port 31 which receives fluid from a suitable high pressure source (not shown), an exhaust port 32 for discharging the fluid to a suitable sump (not shown) and a cylinder port 33 which is connected to the cylinder 26 of the hydraulic engine. These ports provide entry into a valve chamber 38 in which piston 34 reciprocates. The locations of these ports, the length of the piston 34 and its stroke are coordinated such that port 33 may be connected to either port 31 or 32 or may be closed by the piston leaving ports 31 and 32 open to chamber 38. The length of. piston 34 is greater than the axial dimension of port 33, thereby providing an overlap. The leveling valve 46 includes an intake port 47 and an exhaust port 48 which are connected to the main control valve ports 31 and 32, respectively, and a cylinder port 4 9 which is connected tothe port 33. The location of these ports and the length and stroke of a piston (not shown) on the piston rod 45 are coordinated such that port 49 may be connected to either port 47 or 48, or may be closed by said pistomleaving ports 47 and 48 open in the leveling valve 46.

As is shown in Figure" 3, piston 34 is positioned on piston rod 35 which is in. turn supported by stuff ng. box glands 36 and 37. One. exposed end t piston rod 35 is journaledto aconnec tor lllwhichis pivotallyattached to the centralportiori of a lever 41" by means of a pivot pin 42. A link 43 fulcrums thelower end of lever 41 to the casing; of the valve 31), while the upper end of lever 41 is pivoted to a link 44 which is attached to the piston rod 450i the leveling valve 46, The linkage between piston rod 35 andpiston rod -4-5 provides a Vernier motion to actuate the leveling valve 46.

The other exposed end: of piston rod 35 is journaled to a connector 51 which is attached to one end of a shaft 52. Because it is more desirable that the piston rod 35 be non-rotatable, the end of shaft 52 is supported by anend bearing 53 on the connector 51 with the result that the valve shaft 52 is subject to rotation and translation but only translation is imparted to the piston rod 35. Rotary motion is transmitted to shaft 52 by a fluid motor FM through suitable reduction gearing 54. Flexible coupling 55 couples the left and right sections of shaft. 52. I A threaded screw, 56 having a steep pitch is formed on the. left section. of shaft 52 and the length of this screw corresponds to the distance traversed by the piston. rod 35 in opening and closing the valve ports.

The other end of the shaft52 is journaled to. a con-- nector 57 which is attached to a stop lever 60 by a linkage 61. Adjustablescrew stops 62 and 63 limit the move ment of stop lever 60. The upper end of lever 60 is keyed to one end of a shaft 64 supported by a journal bearing 65 (Fig. 2.) while a T-lever 66, including arms 6768, is keyed to the other end of shaft 64 so that lever 60, shaft 64; and T-lever 66rotateas a unit. Oppositely. disposed arms 67 and 68,. on the T-lever 66 sup port rollers 70 and 71, respectively, ftlr a purpose to be described hereinafter. V I v In Figures 2 and 3 auxiliary cams'l-Z and 73, shown. on one side of plungerv follower 28, are adjustably mounted by means of threaded post 74 andlthreaded, stud 75. Cam 72 is positioned on the left end of plunger follower 28 to engage the roller 70 when the platform is located atthe flight deck ll while cam 73 is positioned on the right end of the follower-Ito engage roller 71 when platform 10 is located at the hanger deckj 12.

Gear raclc76- is secured to plunger follower 28 on the side opposite to the auxiliary cams 72- and 73. 7 Movement of the follower 28 causes rotation of a pinion 77 meshing. with the gear rack 76; Pinion 77 drives gear 78 that is keyed to shaft- 80.which extends into gear housing 81 and has a bevel gear. 82- fixed to its end for rotation therewith. A bevel gear 83 meshes with gear 82 at right angles'thereto and is fixed onto a nut 84, tov transmit rotary motion to. said nut 84. The threaded portion 56 of shaft 52 is located within the housing 81, to mesh with the threads or, nut 84. The-arrangement of nut 84 and'the construction of housing 81 is suchIthafl the nut is' restrained from axialfmoveinent butis free. to rotate on the threads 56. i i H l An up. acceleratingcam 85 and a down decelerating. cam 86 are mounted on one end of the plunger renewal 28 and a down accelerating cam 87 and, upIdecelerating cam 88 are mountedo n the oppositeend of this plunger follower. These four cams are so positioned as tocontr'ol the speed of fluid'motonEMfwhen theplunger follower.

28 nears the extremities of itsmovement. The lengthof each cam 85, 86, 87 and 88 (Figure 4) corresponds to the distance of elevator travel in its acceleration and deceleration zones while the contour of each cam corresponds to the desired rate of change of speed of the elevator as it travels through said zones. The cam contours may be varied according to the requirements of a particular installation.

A hydraulic Control system for controlling the fluid.

h sgh. app o t p n eneration r m lve -r d and in turn supply fluid motor FM. Each direction valve, DV and DDY, n ude h e p s; nlet par s.

10 mo r port 10 .7103. a id utlet por s 1.047105. Each valve also, includes three pistons 108 through 113' mounted on piston rods 106- and 1077-. Pistons 108 and 109 are contained within respective pressure differential chambers 1 14. and 115 of each valve, and together with. thefluid connections 133. and 13,4 of valve, UDV and 1 5 3 and 154 of valve DDV, provide means for motivating;

the valve. 'As the pressure on the front or back of P on .98 m 1& hwh mhs fi. .1 n 1 .5 r as s or decreases, the respective piston is moved to the right or le ft within'its chamber, and. in so doing moves its conjugatepistons 110 and 112 or 11 1 and, 113to open or closethe inlet, motor or outlet ports of the, respective.

valve. Cam followers or rollers l lfi and. 117 are mounted on the free ends of pistonrods lfldand 107. As is. indicated in Figure 4, these. followers ride on the surfaces of the cams mounted on plunger follower 28 (Fig. 3 in. such fashionthat follower 116 contacts the surfaces of up accelerating cam,86 and up decelerating cam 87., and follower 117 similarly, the down accelerating cam 88 and downdecelerating cam 8 5,

Flow control valve FCV is. interposed. between the.

outlet ports 104 and 105 of direction valves UDV and QIQV andsumpS. It provides a means for limitingthe maximum speed of motor FM and the elevator by limit ha h nhunt of flui h t LflQ in h nes to n ram h t mo or an he. irec ion valv s- Each directional valve isactuated through itspressure difierential chamber 114 or by fiuid suppljqd from its associated pilot valve UPV, and DPV. Each pilot valve sl d sl f iser. flf n h ted n ts Piston. o

1' 2 2 or 123, which rod is in turn connected, at its right 3 end to the armature of s'olenoid l lfior 127 and; at itsleft en j b. a vspring 2. 25! Eash is q 0 m lv as 2 paitso ha n rq sh tsg dmoamus d, that one or the other pair of channels are in register with; the ports connected to pipe copnections 132,133, 136, etc. for each of the two positionsof the piston.

hus ts haht va d. ta i position... wh hh the as h i i dl qlhn d is tr ed. sp n .2 125 v s i Pi .20 s, ht. phs t on, ch an.

he. ra se hannels. a e pera ive t nts w ths t hr as io s .331 9 3 t hn stionsi n and. .3 r P P YslY.-.

P, n id whrilot Y UB La stQP s ann hea m t h Q l he. n it qt staa 1 2 shu e: valve SV which in turn controls the motivation of brake h khih risttms f he,p lot.valr apiswal a flu d. co d ct ng..- hannel hrough. itsh v hes h ns n Maha ma r i t w th-Pine, wnn s sns 1& and 159. Piston 139" is movedto, its or. left,

Bas o s. y: he ar h tieh. Qt h dra ts.. or e thou thanEd e is e iwlr- I v Fressure release valves 165 and 166 are connected in,

parallel with motor FM across lines 141 and 161 and individually provide unidirectional circulatory paths through the motor in the event of some untoward happening whereby motor FM becomes driven by elevator movement acting through the screw 56 nut 84 combination (Fig. 3). g

As is illustrated in Figures 6 and 7 a safety valve is incorporated in the main control valve 30 to prevent a dangerously rapid descent of the elevator platform if a rupture should occur in the piping. The quick closing valve 200 is positioned between cylinder port 33 and valve chamber 38 to control the flow of fluid from the cylinder 26 to the main control valve 30.

The valve casing 201 is inserted in one side of the main control valve 30 and secured thereto by any suitable means. The threaded portion 202 of the valve oasing receives a valve cap 203 having an aperture 204 centrally positioned therein. One end of a piston rod 205 protrudes through said aperture and a piston 206 connected to the internal end of said piston rod 205 reciprocates in a cylinder 207. Between the valve cap 203 and the outer end of the piston 206, a spring retainer 210, surrounded by a coil spring 211, is adjustably secured to the piston rod 205. An oil ring 212 and a bracket 213 are fixed on the inner end of the piston 206 and a rack 214 is secured to the bracket 213 for movement therewith. Energy stored in the spring 211 causes inward movement of the piston 206 and the rack 214 which meshes with a pinion 215 centrally located on a shaft 216 to transmit rotary motion to the shaft 216. A pair of bevel gears 217 and 218, attached to opposite ends of the shaft 216, are utilized to actuate a pair of shutters 220 and 221 by meshing with shutter gear segments 222 and 223, respectively. Each gear segment is rotatably secured to one end of its corresponding shutter and the gear segment and the shutter are supported by a loosefitting pivot pin at 224 and 225. The barrel portion of each shutter is fashioned into an arcuate section as is the corresponding contiguous surface portion of the valve wall. This forms a partial cylinder and socket joint 219 or 229 such that the thrust of the fluid on the closed shutters is borne by the valve wall rather than by the pivot pin 224 or 225.

The shutters 220 and 221 are disposed within that portion of the main control valve which connects the cylinder port 33 to the main valve chamber so that the shutters are responsive to the fluid pressure in the system. The upper edges of the shutters are oppositely beveled at 226 and 227 which a'but each other when the shutters are rotated to a closed position as indicated by the dashed lines in Fig. 6. Each shutter comprises a plurality of leakage slots 230 along its lower edge interconnected by a longitudinal groove 231, which permit fluid flow therethrough when the shutters are in a closed or opened position. While in the open position the shutters are prevented from engaging the walls of the valve 30 by suitable stops 232 and 233 so that there is fluid flow on each side of the shutters. With such an arrangement there is equalized pressure on both sides of each shutter preventing the shutters from adhering to the stops or the valve walls and insuring facility of operation with a quick action response.

When fluid is first introduced into the system, the fluid pressure on the shutters 220 and 221 causes them to rotate to an open position with their gear segments 222 and 223 meshing with the bevel gears 217 and 218, respectively, to rotate the shaft 216 and its pinion 215. The rotary motion of the pinion 215 on the rack 214 causes the outward longitudinal movement of the piston 206, the connected piston rod 205 and spring retainer 210 which, in turn, compresses the coil spring 211. A decrease in the fluid pressure below a predetermined value closes the shutters in response to the energy stored in the coil spring 211.

' If a rupture should occur in the low pressure exhaust anew piping while the elevator platform is descending, the quick closing valve will remain open because normal pressure conditions would exist between the cylinder 26 and the valve chamber of the main control valve 30 and the exhaust port 32 in the main control valve 30 would be closed by the action of the automatic stop 63, as described above.

If a rupture should occur in the high pressure intake piping while the elevator platform is ascending, the resulting loss of pressure would permit the coil spring 211 to actuate the rack 214 and pinion 215 closing the shutters 220 and 221, thereby cutting off most of the fluid passage. However, fluid would continue to flow from the cylinder 26 through the leakage slots 230 in the shutters, permitting the elevator platform to descend at a slow speed until it reacihes the hangar deck.

Next to be described is the sequence of operations whereby the raising and lowering of the elevator are controlled by the operation of the elements of the hydraulic control system. When the elevator platform 10 is parked at the flight deck 11 (Fig. 1), the plunger 25-is in its extended position and no appreciable amount of fluid flows in the control system. Each directional valve UDV and DDV (Fig. 5) and its respective pilot valve UPV or DPV is maintained in its static or unactivated positionthat is, as is shown for UPV and UDV in Figure-5. There is no fluid flow through the shuttle valve SV and the spring-applied hydraulic brake B engages shaft of fluid motor PM. In this condition, fluid from source HP is fed equally through ports -102 of valve UDV and ports 101-103 of valve DDV to both sides of motor FM. In this state of equilibrium this motor does not rotate. Assume now that solenoid 127, associated with down pilot valve DPV, is energized by any suitable means to cause it to assume the position shown in Figure 5 and to start the elevator on a downward trip to hangar deck 12. The up directional valve UDV re-' mains in its unactivated position because fluid from the reducing valve V-red through the pipes 130, 131, 132, the up pilot valve UPV and the pipe 133 to the hydraulic diiferential device 114 exerts pressure on the rear face of the piston 108. Any fluid in the firont end of device 114 is exhausted through the pipes 134, 135, the up pilot valve UPV, the pipes 136 and 137 to the sump S.

Energization of solenoid 127 actuates the down pilot valve DPV by moving its piston 121 to the position shown in Figure 5 to actuate the down directional valve DDV. Fluid pressure from the reducing valve 'V-red, through the pipes 130, 151, 152, the down pilot valve DPV and the pipe 154 to the hydraulic differential device exerts pressure on the front face of piston 109. Movement of the piston 109 forces the fluid in the rear of device 115 through the pipe 153, the down pilot valve DPV, the pipes 156, 157 and 137 to the sump S. Actuation of the down pilot valve DPV also causes actuation of the shuttle valve SV because the fluid pressure from the reducing valve V-red, through the pipes 130, 151, 152, the down pilot valve DPV, the pipes and 158 exerts a pressure on the right side of piston 139 of the shuttle valve SV to complete the fluid circuit through the shuttle valve SV, the pipe 159, the brake B, the pipes 160 and 137 to the sump S, causing the release of the spring-applied hydraulic brake B. Movement of the shuttle valve SV also forces the discharge of any fluid on the left side of piston 139 through the pipes 138, 135, the up pilot valve UPV, the pipes 136 and 137 to the sump S.

Movement of the piston 109 to the right closes the inlet port 101 and opens the outlet port 105 of valve DDV to complete. a fluid circuit for the fluid motor PM from the reducing valve V-red, through the pipes 130, 131, inlet port 100 and motor port 102 of the up directional valve UDV, the pipe 141, the fluid motor FM, the pipe 161, motor port 103 and outlet port 105 of the-down directional valve DDV, the pipe 162, the flow control 7 valve FCV, the pipes 163 and 137 to the sump S. Movement of the piston 109 brings the cam roller 117 into engagement withthe down accelerating cam 88' thus preventing the" immediate fullactuation of the down directional valve DDV. At this time the restricted flow through motor FM rotates the motor shaft 90 at a slow speed which is transmitted to the shaft 52 (Fig. 3) by means of the reduction gearing 54. Since the restrained nut 84 is not yet rotating, the threaded portion 56 of the rotating shaft 52 is translated through the restrained nut 84 causing the piston 34 to move to the right so that fluid will flow from the cylinder 26 through port 33' to the exhaust port 32. As the elevator starts to descend the plunger follower 28 moves to the right and the pressure on the front face of piston 109 in the hydraulic differential device 115 forces the cam roller 117 to follow the down accelerating cam 88'. The contour of cam 88 controls the rate of actuation of the down directional. valve DDV which in turn controls the acceleration of fluid motor FM.

When the elevator descends out of its acceleration zone, the plunger follower 28 has moved the down accelerating cam 88 past the cam roller 117, so the down directional valve DDV is fully actuated. The pressure on the front face of piston 109 retains the down directional valve DDV in its actuated state which assures unrestricted flow to rotate the fluid motor PM at a constant maximum speed. At this time the piston 34 permits full flow from the cylinder 26 through the port 33 to the exhaust port 32 Fig. 3) and the resulting movement of plunger 25 and plunger follower 28 transmits rotary motion to the restrained nut 84 at a speed approaching the rotary speed of the shaft 52. When the rotary speed of the nut 84 coincides with the rotary speed of the shaft 52, the axial movement of shaft 52 ceases and the piston 34 remains stationary in the main control valve 30 causing the elevator to descend at a constant speed. If the rotary speed of the nut 84 exceeds the rotary speed of the shaft 52, the shaft 52 is axially moved in the opposite direction and piston 34 will restrict the fluid flow from the cylinder 26; consequently, the piston 34 in the main control valve 30 will seek a position which will maintain a direct ratio between the rotary speeds of the nut 84 and the shaft 52. With such a self-seeking piston arrangement variations due to load and changes in the fluid viscosity due to temperature changes are automatically compensated for by a variation in the flow area.

When the elevator reaches its decelerating zone, the plunger follower 28 has moved to a point. where the down decelerating cam 85 engages the cam roller 117 to forcibly move the attached piston rod 107' in. the down directional valve DDV. The contour of the cam 85- determines the rate of tie-activation of the valve DDV and the fluid flow therethrough is reduced in a corresponding varying rate. The resulting decelerated speed of the fluid motor FM causes diiferent speeds of rotation between the shaft 52 and the restrained nut 84 so that axial movement of the shaft 52 moves the piston 34 in the main control valve 30 to restrict the fluid flow from the cylinder 26 through the port 33 to the exhaust port 32 and thus decelerate the elevator platform 10.

In the event of failure of the fluid motor PM, the deceleration of the elevator is controlled by the auxiliary cam 72 (Fig. 3) on the plunger follower 28. The engagement of the cam roller 70 with the auxiliary cam 72 rotates the levers 66 and 66 as a unit causing axial movement of the shaft 52 whereby the piston 34 restricts the fluid flow from the cylinder 26 through the port 33 to the exhaust port 32. This fluid flow is decreased gradually to decelerate the elevator because the axial motion transmitted to the shaft 52 by the lever 60 is dependent upon the sloping contour of the auxiliary cam 72. The axial movement of the shaft '52 is limited by the screw stop 62 to prevent over-travel of the piston 34 in the valve chamber 38.

In order to level the elevator after the main control valve 30 is closed, the final axial movement of the shaft 52 is transmitted to the piston rod 45 of the leveling valve 4'6. The axial movement of the piston rod 45 causes its associated piston to restrict the fiuid flow from the cylinder 26 through the leveling valve exhaust port 48' to the exhaust port 32 and the mechanical linkage 40, 41 and, 44 between the two piston rods 35 and 45 provides a- Vernier motion for the leveling operation.

I At a predetermined time the plunger follower 28 engages a limit switch (not shown) to tie-energize the solenoid 127 permitting. the. coil spring 125 to return and retain the down pilot valve 'DPV to its static position whereby' fluid flow through the brake B is cut off and the brake B engages the fluid motorv shaft. 90. At this time the down direction valve DDV is fully returned and retained in its static position because the fluid pressure from the reducing valve V-red, through the pipes 130, 151, 152, the

- down pilot valve DPV and the pipe 153 to the hydraulicdifferential device exerts a pressure on the rear face of piston 109-. Movement of piston 109 forces the exhaust of fluid in the front chamber of device 115 through the pipe 154, the down pilot valve DPV, the pipes 156, 157 and 137 to the sump S.

The return of the down directional valve DDV to its static condition establishes equalized pressure on the fluid motor FM through the two parallel circuits 131 and 151 leading from the reducing valve V-red.

Operation of the elevator in the up direction is con trolled in the manner just described for the down direction except that solenoid 126 of up pilot valve UPV isv actuated, and the cam roller 116 engages the up accelerating cam 86v and the up decelerating cam 87 to regulate the actuation of the up directional valve UDV.

As it will be understood that this invention is susceptible to modification in order to adapt it to different conditions without departing from the scope thereof, it is intended that all matter contained in the above descrip-v tion or shown on the accompanying drawing shall be in terpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a hydraulic control system, a fluid motor adapted to control machinery, a hydro-mechanical brake on said motor, a directional valve for each direction of rotation of said motor to regulate the speed of said motor, a pilot valve for each directional valve, means to actuate each pilot valve, said pilot valve in its static condition maintaining its corresponding directional valve in a static condition and being operable to maintain said corresponding directional valve in an actuated position, a shuttle valve operable in response to the actuation of one of the pilot valves to release said brake on said motor, and means connected to said machinery to regulate movement of each directional valve and thereby control the acceleration and deceleration of said motor.

2. In a hydraulic control system, a fluid motor adapted to control machinery, a hydro-mechanical brake on said motor, a directional valve for each direction of rotation of said motor to regulate the speed of said motor, a pilot valve for each directional valve, means to actuate each pilot valve, said pilot valve while in a static condition maintaining its corresponding directional valve in a static condition and being operable to maintain said corresponding directional valve in an actuated position, a

shuttle valve operable in response to actuation of one of the pilot valves to release said brake on said mo tor, acceleration and deceleration cams for each directional valve to control the rate of actuation of that di recti-onal valve, said cams being connected to said ma chinery whereby the acceleration and deceleration of said motor are responsive to the operation of said machinery.

3. .A hydraulic control system for a hydraulic hoisting machine, said machine being energized from a fluid source, control valves connecting said fluid source to said machine for controlling the operation of said machine, valve actuating means to open and closed said control valves, a diiferential mechanism connected to said valve actuating means and being operable in response to the operation of said machine, a fluid motor and reduction gearing also connected to said valve actuating means, directional valve means for connecting said fluid motor to said fluid source to control the direction and speed of rotation of said fluid motor, cam following means on said directional valve means, and cam means positioned on said machine, said directional valve means being controlled in operation by said cam following means engaging said cam means on said machine whereby the speed of said fluid motor is controlled by the operation of said machine and whereby the differential effects of operation between said machine and said fluid motor causes operation of said valve actuating means.

4. A hydraulic control system for a hydraulic hoisting machine having a plunger operating in a cylinder, a relatively high pressure fluid source, a control valve connecting said cylinder to said fluid source and having an intake port and an exhaust port, said control valve having a piston rod and piston operable to regulate the flow of fluid from said intake port to said cylinder for controlled movement of the plunger in one direction and from said cylinder to said exhaust port for controlled movement of the plunger in an opposite direction, a valve shaft connected to said piston rod and adapted to move longitudinally to actuate said piston in opening and closing said control valve, a fluid motor and reduction gearing connected to said valve shaft for transmitting rotary motion thereto, a differential mechanism operated in response to movement of said plunger, means rotated by said differential mechanism and connected to said valve shaft whereby different speeds of rotation between said valve shaft and said connecting means causes longitudinal movement of said valve shaft, and a servomechanism controlling the speed of said fluid motor comprising directional valves actuated by acceleration and deceleration cams connected to said plunger for movement therewith, said directional valves controllably connecting said fluid motor to said fluid source, whereby the rotary speed transmitted to said valve shaft is dependent upon the position of said plunger operating in said cylinder.

5. A hydraulic control system for a hydraulic hoisting machine, a fluid source of motive energy, a control valve connecting said fluid source to said machine for controlling the operation of said machine, valve actuating means to open and close said control valve, a fluid motor and reduction gearing to transmit rotary motion to said valve actuating means, a differential mechanism operated in response to movement of said machine, means rotated by said differential mechanism and connected to said valve actuating means whereby different speeds of rotation between said valve actuating means and said connecting means causes actuation of said valve actuating means, a pair of directional valves connecting said motor to said fluid source, one of said directional valves for each direction of rotation, to control the speed of said fluid motor by regulating fluid flow through said motor, a pilot valve for each directional valve, each plot valve while in its static condition maintaining its corresponding directional valve in a static condition to prevent fluid flow through said motor, means to actuate said pilot valves, the actuated state of one of said pilot valves maintaining its corresponding directional valve in an actuated position to permit fluid flow through said motor, a cam follower on each directional valve controlling the movement thereof, and an acceleration and a deceleration cam for each directional valve, said cams being positioned on said machine and engaging their corresponding cam followers to regulate the fluid flow through said fluid n'1o tor whereby the motion transmitted to said valve actuating means by said fluid motor and reduction gearing is controlled according to an operating condition of said machine.

6. In a hydraulic elevator, a hydraulic machine having a plunger operating in a cylinder to raise and lower an elevator platform connected thereto in response to a motive fluid flowing into and out of said cylinder from a fluid source, a control valve connecting said fluid source to said cylinder and having inlet and outlet ports, said control valve having a longitudinally movable piston and piston rod adapted to open and close said ports, a rotating valve shaft connected to said piston rod, a fluid motor and reduction gearing connected to said valve shaft and operable to transmit rotary motion thereto, a plunger follower connected to said plunger for movement therewith, a gear rack secured to said plunger follower, a gearmechanism meshing with said gear rack, a restrained nut meshing with said gear mechanism whereby movement of said plunger follower transmits rotary motion to said restrained nut, a threaded portion on said valve shaft meshing with said restrained nut whereby different rotary speeds between said restrained nut and said valve shaft causes longitudinal movement of said valve shaft,

means to control the rotary speed of said fluid motor comprising up and down directional valves connecting said fluid source to said fluid motor, and an acceleration cam and a deceleration cam for each directlonal valve, said cams being positioned on said plunger follower and engaging their corresponding directional valves to control the rate of movement thereof whereby the acceleration and deceleration of said fluid motor controls the speed of rotation transmitted to said valve shaft in response to the position of said plunger follower.

7. In a control system for a hydraulic elevator, a fluid motor adapted selectively for rotation in either direction, a hydraulically released, mechanically applied brake connected to said motor, a pair of directional valves operatively associated with said fluid motor, a pair of pilot valves, each one of said pilot valves being individually connected to a respective one of said directional valves, means individual to each pilot valve to control the actuation of that respective valve, means operatively associated with each of said pilot valves and its respectively associated directional valve for moving the associated directional valve from its static condition to its actuated condition upon actuation of the respective pilot valve, a shuttle valve operable in response to the actuation of either of one of said pilot valves whereby hydraulic fluid is supplied to said hydro-mechanical brake to release said brake on said motor, and means associated with each directional valve op'eratively to control the movement of said directional valve conjointly with the respective pilot valve whereby the acceleration and deceleration of said motor is conjointly controlled.

References Cited in the file of this patent UNITED STATES PATENTS 1,980,356 Raber Nov. 13, 1934 2,409,198 Dunlop Oct. 15, 1946 2,409,199 Dunlop Oct. 15, 1946 2,423,516 Naab et al. July 8, 1947 2,618,121 Tucker Nov. 18, 1952 2,660,985 Ernst Dec. 1, 1953 2,789,542 Vander Kaay Apr. 23, 1957 

